Tunnel kiln



Aug. 14, 1934. s. M. KIER ET AL TUNNEL KILN Original File June 2l, 1930 4 Sheets-Sheet ll {lIL ug. 14, 1934. s, M, KIER ET Al.

TUNNEL KILN Original Filed June 2l, 1930 4 Sheets-Sheet 2 Nm NN @n Aug- 14 1934- s. KIER ET Al. 1,970,320

TUNNEL KILN original Filed June 2l. 195o 4 Sheets-sheet 3 Samuel M. Kiev Fran K M Hartford Aug. 14, 1934. s M K|ER ET AL TUNNEL KILN Original Filed June 21, 1930 4 Sheets-Sheet 4 Samuel NLKier FanK. M. Hartford duowmj Patented Aug. 14, 1934 www 1,970,320 TUNNEL iriLN Samuel M. Kiel', Salina, Pa., and Frank M. Hartford, Columbus, Ohio 25 Claims.

This inventionv relates to continuous kilns of the Vtype used in the burning or heat Vtreating of clay ware. Kilns of this type are characterized by the provision of a wall and roof Struc- 5 ture which forms a longitudinally extending passage `or tunnel through which kthe ware, arranged on horizontally movableV platforms, is advanced progressively, and wherein provision is made for developing desired operating temlO peratures within the tunnel in order to subject the ware to the desired degree of heat treatment during its passage through the tunnel.

The invention has for one object the provision of a tunnel kiln which is `formed to comprise l5 transversely spaced longitudinally extending side walls and a flat suspended roof having its lower surfaces, which define the top wall of the tunnel, arranged in a uniform substantially horizontal plane, whereby the ware may be disposed on the movable platforms in settings having a desired structure and stability and yconforming closely to the roof plane and in uniform proximity thereto, to obtain uniform distribution of heated gases over the tops of the setting and longitudinally o-f the tunnel and also to obtain the maximum benefit of the radiant heat released from the refractory walls and roof of the tunnel.

Another object of the invention resides in the l provision of a tunnel kiln constructed to permit of the passage of a `large quantity of ware through the kiln on a plurality of cars arranged in two or more trains movable side-by-side through the tunnel but wherein the car units comprising the trains are interchangeable and may 1oe conveniently separated and handled individually eirteriorly of the tunnel, facilitating thereby the placing of the ware on the car units or the removal of the ware from such units;

the installation affording large capacity and uniform burning effectiveness together with facility and ease in the matter of handling the products delivered to and removed therefrom.

In tunnel kilns now in use, designed to accorninodate a single train of car sections, the

tunnel is heated by the provision of heat generating devices associated with the side walls of the tunnel and on opposite sides of the warecontaining car sections. In a single track tunnel of limited width such heating arrangement is usually sufficient to effect a fairly uniform heat treatment of the ware, but in multi-track tunnels,v or tunnels of extended width, of the type to which the present invention is particuv larly directed, the increased width of the tunnel and ware setting necessitates the employment of additional heat generating appliances, in order that all portions of the ware comprising such settings will be subjected for the proper period of time to necessary temperatures for effecting the burning or complete maturing of such ware. Therefore, the present vinvention provides for the application and distribution of high burning or maturing temperatures not only along the sides of the settings, but particularly in the central and lower central regions thereof, and also the control of the heating in the upper central regions of the settings, this being accomplished by the introduction of heat generating and developing media through the roof of the kiln in a manner and under a control such that the location of the combustion zone with respect to the setting may be definitely predetermined and governed.

It is .a further object of the invention to place the ware on the car platforms to produce a plurality of longitudinally extending passages between adjacent sections of the settings and hetween the side walls of the tunnel and said settings and wherein the burner devices operating through the roof serve to introduce a fuel for combustion in said' passages in order that said burning of said fuel in the passages may directly deliver to the setting the required temperatures necessary to effect proper heat treatment of all portions of the ware, avoiding specifically lack of uniformity in heating of the entire mass o'f such settings.

A further object of the invention rests in the provision of a tunnel kiln provided with a suspended roof which consists of a plurality of refractories suspended from metallic cross members supportedv in conjunction with the side walls of the kiln, and wherein the mounting or suspension of said refractories is such as to permit various units thereof to be removed bodily from the kiln to provide convenient and immediate accessto the interior of the tunnel through the roof, for the purpose of facilitating repairs or to relieve congestion due to the fallingor shifting of the position of a setting on a car.

With these and other objects in view which will appear as the description proceeds, the invention consists in the novel features of constructions, combinations of elements and arrangements of parts, hereinafter fully described and pointed out in the appended claims.

In the accompanying drawings:

Figure 1 is a horizontal sectional View taken through a tunnel kiln constructed in accordance with the present invention,

Figure 2 is a similar view taken through the cooling zone of the kiln on the line 2-2 of Figure 1,

Figure 3 is a vertical cross-sectional view taken through the maturing Zone of the tunnel on the plane indicated by the line 3 3 of Figure 1,

Figure i is a vertical longitudinal section of the roof structure of the kiln,

Figure 5 is a vertical transverse sectional View' disclosing the single track kiln constructed in accordance with the present invention and formed with a suspended roof structure,

Figure 6 is a still further modification disclosing a single track-arch-roof kiln provided with roof burners disposed in accordance with the features of the present invention,

Figure 'Z is a detail vertical sectional view illustrating the modied form of roof structure wherein the refractories are suspended from transverse supporting members, and

Figure 8 is a similar view taken through a kiln provided with a center row of roof burners and illustrating by broken lines the regions of the ware settings directly affected by the high temperaturesV produced by said burners.

Referring to the illustrative examples of structure shown in the drawings, the numeral 1 designates a tunnel kiln embodying the present invention. The kiln comprises an elongated masonry structure, the walls of which are formed of suitable heat resisting material. The construction is such as to provide an elongated tunnel or passageway which extends longitudinally through the kiln, the said tunnel being indicatedby the numeral 4. The opposite ends of the kiln are open or provided with hinged doors,

, so that cars or other small portable carriers or conveyors may be moved into the kiln at one end, passed through the tunnel, and out or^ the other end thereof. The entrance end of the tunnel is indicated by the numeral 5 and the discharge end by the numeral 6. At a point approximately midway of its length the wall structure 3.0i the kiln may be provided with a battery of` furnaces, indicated at 2, which communicate with the tunnel and may be red in any suitable-manner partially to develop the requisite temperatures to properly lre the particular ceramic bodies passed through the kiln. The cars or `other movable and portable carriers 7 which carry `the ceramic wares to be red, are moved progressively through the tunnel, in this' instance along a pluralityY of trackways 8, and as the cars so advance through the tunnel from the entrance, the ware suitably piled thereon, encounters rst water-smoking and dehydration Zones 9 and 9 of progressively increasing temperature. During the passage of the cars through these zones moisture is driven from the ware and the latter is conditioned for the higher burning or oxidation temperatures prevailing in the Zone Siu.l Continued advance of the cars or carriers brings the ware into the high temperature or maturing Zone 10, which is disposed approximately midway of the length ofthe tunnel or as determinedby the location of the furnaces and the rate of travel of the cars determines the period of time that the goods progressively decreasing or ware are subjected to these` high burning or tiring temperatures. Further progressive advance of the cars removes the ware from the high temperature Zone 10 into a cooling zone of temperature, which cooling zone is indicated by the numeral 11, so

that by the time the Ware is discharged from the end 6 of the tunnel its temperature has been reduced to a point such that it will not be adversely affected by the room temperature, and the burning ware may be removed from the cars or carriers. The latter may be advanced through the tunnel by suitable means either intermittently or continuously. Cold air is introduced adjacent the discharge end of the cooling Zone and passed through the tunnel to expedite the cooling and to supply preheated air for use in combustion in the maturing zone.

With reference to the specic details of the kiln here shown-for `purpose of illustration, there is employed a concrete foundation or base 12. Upon this foundation is supported the wall structure 3 which includes a pair of spaced substantially vertical side walls 13-13, composed of brick, the inner portion being of re brick, or other refractory material.V The side Walls are of suitable thickness to minimize heat loss through radiation or other escape to the atmosphere and, if desired, said side walls 13 may be provided with a lagging 1li of heat insulating material. Secured Ain the foundation Y12 and ranged along the exterior planes of the walls 13 are vertically disposed structural members -or buckstaysl, to the upper ends of which are secured transversely extending` roof-supporting beams 16. The cross members 16 may rest onY theside walls 3 and may be detachably-bolted to brackets 17 on the upper portions of the buckstays 15. This 'construction is such that by disconnecting the cross members 16 from the buckstays, the said cross members, together with the portions of the roof structure suspended therefrom, lmay be elevated bodily over localized areas, providing thereby for convenient access to the interior of the tunnel through the roof of the kiln.

The roof of the kiln additionally comprises a plurality of refractory blocks 20 which are preferably though not necessarily arranged in a horizontal plane and form, when assembled, a substantially flat roof. These locks have their upper surfaces formed with T-shaped slots 21, which slots receive the flanged lower edges of cast iron arch bars 22 which are demountably suspended by hanger rods 22a from the cross members 16. The blocks 2O at the longitudinal edges of this roof structure overlap shoulders 23 provided on the upper portions of the side walls 13, the joints between the side walls and the blocks 20 being sealed with a compressible refractory or other suitable sealing material asV indicated at 24. This allows for relative movement between the blocks comprising'the roof structure and the vertical side walls in response to varying kiln temperatures and other conditions, and at the same time keeps these joints sealed to prevent leakage. The length of the arch bars 22 is less than the distance between the beams 16 from which they are suspended, and' to close the space between the refractories 2O supported on aligned arch bars. similar refractories 20a are supported on flanged bridge castings 23, the heads of which rest on top of the refractories 20 on the adjacent arch bars. The bridge castings 23 and refractories 20a are disposed below the beams 16, and they may be withdrawn upwardly from' thereof, so as to permit the roof sections carried on respective arch bars 22 to be elevated individually between the beams.

This iiat suspended roof is in marked contrast with the usual arched masonry roof'heretofore generally employed in kilns of this character, and

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permits the tunnel 4 to be of any desired width. The use of the usual arched masonry roof imposes limitations on the width of the tunnel. Use of a suspended roof allows almost unlimited latitude in the width of the tunnel, so that as a result a single kiln constructed in accordance with the present invention may have the productive capacity of a plurality of kilns of conventional design. Moreover, this is accomplished without materially increasing constructional costs.

In Figure 1 of the drawings, the tunnel has been depicted as containing a pair of trackways 8, but it should be understood that this number may be varied if desired. Each of the cars or carriers 7 on which the ware is transported through the tunnel comprises a metallic frame carried on track-engaging wheels 26. To protect the metallic frames 25 from the high temperatures prevailing in the kiln each car includes a floor or platform composed of a heat resistant insulating material, such as fire brick.

Between the trackvvays 8 there is provided a divisional wall 29 which, contiguous to its base,

, is formed with longitudinally extending troughs ,Y against the passage of heat and'gases from the heating areas of the tunnel into areas which it is desired to keep relatively cool. Similarly, the outer longitudinal edges of the car floors 27 are provided with depending plates 33, the lower edges of which are received within sand containing troughs 34 formed in conjunction with the lower inner portions of the walls 13. The latter walls are also formed with horizontally and longitudinally extending ledges 35 which overlap the oors 27 of the cars to baffle the passage of heat andk gases from the tunnel d Ainto the wheel areas. By this construction the metallic members of the cars or carriers 7 are protected against overheating.

The ware is piled on the platforms 27 of the cars, either with or without the use of saggers, in vertical order to produce spaced setting sections, as indicated at 36, which arrangement permits the heat of the kiln to pass freely and uniformly around the ware to procure a unifo-rm burning or firing thereof. The hot combustion gases pass from the furnaces 2 directly into the tunnel 4 through openings 37 formed in the side walls 13-13. Also, fuel is injected throughthe burner ducts 38 formed in the roof structure of the setting. The ducts 38 are so placedfthat the discharge of the burners 38 is directed downwardly in the spaces between the setting sections carried on the cars and also, if desired, along the outer sides of the settings. By suitable adjustment of the force of the burner discharge, and the quantity of primary air and fuel fed, the zone of combustion from any burner may be adjusted or positioned vertically relative to the setting so as to apply the heat where desired and thereby, in conjunction with the heat from the lateral furnaces 37, obtain a uniform heating of the entire setting. In an ordinary tunnel kiln the heated gases of combustion enter the tunnel through openings formed in the side walls. However, when multiple tracks are used, and in certain instances single tracks, a more uniform firing action is secured by introducing the combustion producing fuels or gases at a plurality of points along the roof structure, and this is made feasible by the suspended type of flat roof here disclosed.

well as hat types of roofs.

Above the cross members 16 and spaced from the lower row of blocks 20, there is provided a top closure formed of slabs supported on angle bars which rest on spacing blocks laid on the beams l5. This top closure, in conjunction with the lower blocks20, forms a roof duct or conduit closed at the side by the upper portions of the side walls. Air may be introduced into one end of this conduit by means of a blower 51 which may draw its supply from the external air, and operate to force the air longitudinally through said flue for preheating purposes and to limit the temperature of the refractory roof, and preventing overheating of the supporting beams. As the fuel feeding devices 3S pass through this air duct, the fuel and-'primary air introduced through them receives some preheating from the air in the duct. This-preheated air is then introduced directly into the water-smoking Zone 9 of the tunnel for heating and supplying oxygen to the ware in the zones 9, 9 and 9a. The blower 51, or an additional blower, may also introduce cooling air directly into the cooling zone ll of the tunnel to expedite the cooling of the ware and to provide preheated air for admixture with the combustion gases and fuels present in the maturing zone lo in order to effect regulated combustion in said maturing Zone. The walls of the oxidation zone of the tunnel are provided with offsets indicated at 21a which are used to lproduce a tortuous path of travel ofA the gaseous products of combustion through the oxidation zone in a direction generally opposed to that of the direction of travel of the ware through the tunnel. A draft fan 2lb communicates with'the dehydration zone 9 to remove from the tunnel the gaseous products of combustion, which have been largely deprived of their 'effective heat,

The walls of the dehydration and water-smoking zones are provided with ports as at 40 which lead to a transverse exhaust duct 4l withV which communicates a draft fan 2lb for maintaining a `forced passage of the heated gases of combustion through the kiln and the removal of such gases after the desired heattransfer with the ware has taken place. If desired, the ware may be set or placed on a perforate foundation disposed on the platforms of the cars so that the heated gases discharged from the side wall burners may enter such foundation and pass upwardly through the ware disposed thereon. In this manner the ware is heated from the bottom as well as from the top and sides during its passage through the tunnel. It is, of course, within the scope of this invention to apply these features of construction to a single track tunnel as well asto a multiple track installation, and to arched as The divisional wall separating the tracks in the multiple track tunnel may be provided with a conduit fia through which 'air may be forced to cool the surface of said divisional wall and,'if desired, said wall in the entrance end of the kiln may be perforated to assist in withdrawing gases from the tunnel.

The multiple car trains, as previously stated, are particularly advantageous in the handling of the ware. Considerations of convenience and efiicient handling outside the kiln impose limitations o-n the size of the cars. By the multiple track arrangement, the present invention provides, for purposes of kiln capacity, a ware supporting platform approximating the full width of a kiln of extra width, and makes it possible for convenience and Veiiciency in handling, loading and drawing outside of the kiln to employ small SOL esv

cars of a Width which is only a fraction of that of the tunnel. For example, in tunnels possessing a Width of 12 feet, 18 feet, 24 feet, etc., cars of 6 foot Width may be used. The respective trains can be run either at the sameV speed, or at different speeds to provide different time cycles of tunnel occupancy of adjacent trains, since -it may be desirable to load one train of cars With brick and the companion train With other materials requiring either longer or lesser exposure to the tunnel temperatures-- Preferably, the fuel is injected into the vertical passages formed between the setting sections with such velocity and mixture that active combustion thereof takes place contiguous to the lower portions of the settings. As indicated generally by. the dotted curves X in Figure 5, the Wall burners heat. quite adequately the sides of the setting, and While the upper portions of the settingsA are eectively heated from the roof radiation and the high temperatures in the upper portion of the tunneLin-many instances difculty is involvedin thoroughly heating or burning that portion ofthe ware located adjacent 'to the Vcenter and` lower parts of the i setting.v By proper regulation of the roof burners, their zones of combustion may be deiinitely located at an elevation or.v position with respect to the setting sectionsiwhich is appropriate to supply the requisite heat in areas which would be inadequately heated from .the Wall burners alone. Thus a zone of maximiun-heating from the roof burners may be maintained, or example, as illustrated generally by the dotted curves Y in Figure 5, the heating or" the entire setting being thus Ji, equaliaed. Thus the heating zones indicated at a in Figure 5, are heated conjointly by the side wall and the outermost of the roof burners, While the zones b and c, which include the central portions of the ware settings, are heated more directly by the central roof burners. It will be understood that these zones more or less overlapto secure the desired uniformity of heating throughout all parts of the ware settings.

From the foregoing it Will be appreciated that the combination of the at suspended roof With the other elements of the structureaccomplishes several highly advantageous and desirable results.r It completely obviates the limitations as to Width of the tunnel which are the necessary sequela of the use of a sprung arch. The use of the at suspended roof, accordingly, not `onlypermits the per-hour capacity of the kiln to be doubled or tripled, but permits all of the setting sections to be made of uniform height and size and to be subjected to uniform temperature 1conditions.

uniform relationship With respect to the roof, and

thus' toobtain uniforrngas circulaion and uniform backfeed through the tunnel or secondary combustion air. Moreover, it permits the roof duct to be made or uniform cross section and as a result thereof obtains uniform cooling eiiect on the refractory roof from the air passed through the roof duct. This is of importance in obtaining uniform temperatures across the tops of all the setting sections, in which portion of the tunnel the temperatures are most likely to build up and are most diiilcult to limit Without resulting in 'undesirable limitation of temperatures in the It takes a` of .the ware, and the proper treatment of the Ware depends on the maintenance of proper temperatures in the kiln. Under the drying and heating influences to which the Ware is subjected during its passage through the kiln, it is subject at diierent stages to expansion and shrinkage. Consequently, the stacks or sections of the setting, Where the pieces of Ware are piled one upon another, as in the burning of re bricks, may get out of plumb, and in instances Where some of the pieces fracture or fall, a portion of a setting may topple over. Due to the close proximity of the setting sections to the side Walls, such happenings may result in jams which will prevent. the progressive movement of the cars. In such a contingency the removal of the cars of partly finished Ware would involve a great loss of heat and possible injury to the Ware, and the cooling down of the kiln would require a long time and a Very great heat loss. By having the suspended roof sectionally supported, and respective sections individually removable, the roof may be opened directly over Where the jam occurs, and the dislodged portions of the Ware quickly removed and the roof sections quickly replaced, Without material loss of heat and Without detrimental .eiect on the other portions of the kiln charge. it Will be obvious that in the construction herein .shown the roof sections carried on respective arch bars 22a may be quickly lifted out of the roof by comparatively light tackle engaged in the hoisting eyes 2213, after preliminary removal'of the refractories 20a at the ends of such sections. When the sections are replaced and their hanger rods 22a engage with their supporting beams, the sections will be automatically positicned with their lower surfaces in the proper association with the tops of the settings already in the kiln, thus eliminating any necessity for truing of thevreplacedsections preliminary to resuming movement of the train. The free joints between the marginal roof sections and the Walls permit first the removal of a marginal section or sections With facility, after which one or more sections in the same transverse tier may be as readily removed7 until an opening of sufficient size is made to permit the rapid extraction of the dislodged ware from the kiln by means of tongs.. The construction of the top closure is such as to permit its, being opened quickly in areas of any desired extent, to afford access to the suspended roof sections.

What is claimed is:

l. In a tunnel kiln, a wall structure provided with spaced vertical side Walls, cross members resting upon the upper edges of said side Walls and arranged horizontally between said Walls, a plurality of refractory block units arranged in a horizontal plane and suspended from said cross members to form the roof of said tunnel, and a covering carried by said cross members spaced horizontally from said block units to produce a longitudinally extending flue in said Wall structure above said blockunits.

'2.' In a' tunnel kiln, a Wall structure formed to provide a longitudinally extending tunnel, spaced track-ways arranged in the base of said tunnel, portable carriers movable longitudinally through said tunnel over said track-Ways, a divisional wall situated in the base of said tunnel between said track-ways and terminating below the plane of the platforms, of Asaid carriers, and means for circulating a gaseous fluid through the divisional Wall.

3. In a tunnel kiln, the combination with side Walls and a progressively movable Ware supportnews2@ ing' platform therebetween, of a fiat refractory roof extending parallel with the ware supporting platform and conjoining the walls, and a top closure spaced above the refractory roof to'afford therebetween an air duct of uniform height across the roof. Y A 4. A tunnel kiln structure as specified in claim 3 and wherein supporting members for the refractory roof are exposed to air in said air duct. 5. In a tunnel kiln, a heat confining structure comprising spaced side walls and a roof cooperatively related to form a tunnel which extends longitudinally through the kiln from one end thereof to theother, spaced parallel longitudinally movable conveyorsarranged in thebase of the tunnel and upon which conveyors the ware to be heat-treated is positioned for advancement through the tunnel, said ware being disposed in vertical settings to produce therebetween vertical longitudinally extending passages, and burner means mounted in conjunction with both the side walls and roof of the kiln for introducing fuel in a state of active combustion into the vertical passages formed between adjoining settings of the ware and between the side walls of said kiln,

lwhereby said combustion gases contact directly parallel trains of ware carriers movable simultaneously through said tunnel, and burner means arranged intermediately of the length of said heat confining structure for delivering fuel in av vstate of active combustion into said tunnel for "uniform distribution around and in direct contact with the ware positioned on said carriers,

said burner means being mounted in connection with both the side and roof walls of the heat conning structure. '1. In a tunnel kiln, a heat confining structurev tion through said tunnel along said ways, said car- 'riers being adapted to have positioned thereon the ceramic ware to be heat-treated in the kiln, and means arranged intermediately of the length of the tunnel for delivering a combustible fuel into said tunnel for direct contact with the ware through Vboth the side and roof walls thereof.

"tunnel being provided with a plurality of spaced longitudinally extending ways, ware-receiving carriers movable longitudinally along said ways, and a plurality of burners arranged adjacent to said roof and side walls for delivering a heated 'gas of combustion directly into said tunnel intermediate of the length thereof for direct contact with the ware on said carriers.

9. A kiln comprising a longitudinally extending tunnel formed with spaced vertical side walls and an overlying roof structure, said tunnel substantially midway of its length being formed with a high-temperature heating zone, means for advancing ware to be heat-treated longitudinally .through thetunnel, a plurality of burner units provided in the side walls of said high-temperature zone, and a plurality of complemental burner units provided in the roof structure of said hightemperature zone, said latter units being disposed to initiallyy direct the combustion producing materials discharged therefrom downwardly along the sides and central portion of the tunnel into direct contact with the ware passing through said Zone. i

lo. In a tunnel kiln, spaced vertical side walls and an overlying roof structure forming conjointly an enclosed longitudinally extending tunnel, transversely spaced longitudinally extending carriers movable longitudinally through said tunnel, carriers being adapted for the reception of ware to be heat-treated in the tunnel, andl a hollow flue-forming divisional Wall arranged between carriers substantially below the ware positioned thereon andexten-ding longitudinally of theftunnel.

11. In a tunnel kiln, spaced vertical side walls and an overlying roof structure forming conjointly an enclosed longitudinally extending tunnel, transversely spaced longitudinally extending carrers movable longitudinally through said tunnel, said carriers being adapted for the reception of wareto be heat-treated in the tunnel, and a hollow divisional wall arranged in the lower part of said tunnel between said carriers and extending longitudinally of the tunnel substantially below the ware supported on said carriers, said divisional wall being provided with ports establishing communication between a flue formed interiorly of said divisional wall and the interior of said tunnel.

l2. In a kiln, a wall structure lformed to provide a longitudinally extending tunnel passing,

through the kiln from one end thereof to the other, conveying means movable longitudinally through the'turmel and upon which the ware to be heat-treated in the tunnel is positioned, the ware being disposed in spaced settings producing longitudinally extending passages between the adjacent `vertical walls of the settings and the outer vertical walls of the settings and the corresponding inner walls of the tunnel, and means for delivering combustible materials downwardly and vertically into each of said passages for combustion adjacentto the lower portions ofsaid passages.

13. In a kiln, a wall structure formed to provide a longitudinally extending tunnel passing through the kiln from one end thereof to the other, conveying means movable longitudinally through the tumiel and upon which the ware to be heat-treated in the tunnel is positioned, the ware being` disposed in spaced settings producing longitudinally extending passages between the adjacent vertical walls of the settings and the outer vertical walls of the settings and the-correspondinginner walls of the tunnel, and indebustible materials downwardly and vertically into each of said passages for combustion adjacent to the lower portions of said passages.

14. In a kiln, a Wall structure comprising vertical side walls, vertical buckstays arranged exteriorly` of the side walls, horizontally extending cross-members resting upon the upper surfaces of said side walls and connected with the upper portions of said buckstays, a roof for said wall structure composed of a plurality of refractory block units independently suspended from said cross-members and having' the lower surfaces thereof arranged in substantially a horizontal pendently controlled means-for delivering cornplane, and a conveyor passing longitudinally through the kiln for the reception of ware settings to be heat-treated, said ware settings being shaped to closely conform to the substantially rectangular configurationV of the kiln.

15. In a tunnel kiln, 'a wall'structure including vertical side walls, vertical buckstays arranged exteriorlyof said side walls, horizontally extending cross-members supported by the upper edges of the side walls and removably connected at their ends with said buckstays, a roof for said wall structure consisting of a plurality of refractory block units suspended from said crossmembers, said units being removable bodily for cooperation withsaid side walls, said block units having their lower surfaces arranged in a substantially horizontal plane, and a ware carrier movable longitudinally through said kiln between said side walls and below said roof structure.

16. In a tunnel kiln, a wall structure including spaced vertical side walls, a substantially flat roof structure formed in units composed of a plurality of refractory blocks, cross-members arranged over said side walls, means for suspending said units from said cross-members, and a ware carrier movable longitudinally through said kiln between said side walls and below said roof units.

17. In a tunnel kiln, a wall structure comprising a pair of spaced vertical side walls, a roof for the kiln comprising a plurality of suspended refractory blocks arranged in a substantially horizontal plane, a conveyor movable longitudinally through the kiln and having ware placed thereon in substantially rectangular settings conforming to the cross-sectional configuration of the kiln, said ware settings being substantially uniformly spaced from the interior walls of the kiln to receive uniformly radiant heat energy released from the side and roof walls of the kiln, and means for introducing combustible gases into the spaces of the kiln formed between said ware settings and the internal kiln walls.

18.A In a tunnel kiln, a wall structure comprising a pair of spaced vertical side walls, a plurality of horizontal cross-members carried by the upper portions of said side walls, refractory block units Vsuspended from said cross-members and forming a Vhorizontal roof for the kiln, said side walls and roof serving to define conjointly a tunnel extending longitudinally through the kiln, said tunnel being of substantially rectangular cross-sectional configuration, a Ware carrier movable through the tunnel and having ware settings arranged thereon substantially uniformly spaced from the walls of said tunnel, and joints of compressible heat-insulated material provided between the adjoining portions of the block units of said roof and side walls of the tunnel.

19. In a tunnel kiln, spaced side walls and a roof structure forming a tunnel which extends longitudinallyy through the kiln fromv end to end thereof, a carrier movable longitudinally through the tunnel and upon which the ware to be heattreated is positioned in a manner to form vertical longitudinally extending flue passages between said side walls and roof, burners mounted in connection with the roof structure for delivering combustible materials downwardly into said passages, burners provided in conjunction with the side walls of the kiln for delivering combustible gases into said spaces and passages, and means for controlling the operation of said burners to localize the Vhigh-temperatures produced thereby in any desired region throughout the height of the setting.

nordsee' 20. Inf a tunnel kiln, spaced side Walls and a. roof structure forminga tunnel which extends longitudinally through the kiln from end to end thereof, carriers'movable longitudinally through the tunnel and upon which the vware to be heattreated is positioned to form vertical longitudinally extending flue-passages, burners mounted in connectionvwith the roof of the setting for delivering combustible materials to said passages, means for controlling the operation of said burners to regulate the zones of combustion of said materials in said passages, whereby to localize'the high temperatures produced'by the combustion of said materials at any desired region throughout'the height of the setting, and means for regulating the longitudinal travel of the high temperature gases in said flue passages.

21. In a tunnel kiln, the combination with side walls and a movabley ware supporting platform therebetween, cross-members' extending transversely ofthe upper portions of said sidewalls, of a flat refractory roof disposed between the walls, and suspension means uniting said cross-members and roof with the lower surface of the latter parallel to that of the ware supporting platform.

22. AY tunnel kiln comprising: the combination with side walls, of a refractory roof extending between the side walls, a top closure spaced above the refractory roof to form an intervening air duct, fuel feeding devices extending through the duct and discharging combustion gases downwardly through the refractory roof, and complemental combustion devices extending through said side walls.

23. In a tunnel kiln, the combination of an elongated heat conning structure having side walls and a roof arranged to form a tunnel, means for moving Ware progressively through the tunnel, combustion devices projecting through said side walls and arranged to discharge combustible materials into the tunnel in direct contact with the ware, complemental combustion devices arranged to discharge combustible materials into the tunnel and in direct Contact with the ware and extending through the roof of the tunnel, and means for regulating the last-mentioned combustion device to govern vertically the Zones of combustion.

24. In a tunnel kiln, the combination with side and cooperatively spaced tracks disposed between said walls, of supporting members spanning the space between the walls, refractoryl roof sections suspended from said supporting members with rtheir lower surfaces in a common plane to form a roof exten-ding continuously across the tracks and parallel thereto, ware supporting platforms movable progressively in parallel relationship with the roof, burner devices arranged to discharge combustible materialsinto the tunnel formed by said walls and roof sections. f v

25. In a tunnel kiln, the combination with side and cooperatively spaced tracks disposed between said walls, of supporting members spanning the space between the walls, refractory roof sections suspended from said supporting members vwith their lower surfaces in a common plane to'form a roof extending'ccntinuously across the tracks and parallel thereto, ware supporting platforms movable progressively inv parallel relationship with the roof, burner devices arranged to discharge combustible materials into the tunnel formed by said walls and roof sections, and combustion devices arranged to discharge downwardly through the roof sections combustible materials.

' SAMUEL M. KIER.

FRANK M. HARTFORD. 

